Various types of low volume water sprayers and drip irrigators are known for agricultural applications. Generally speaking, they all share certain common goals, provision of a generally low volume, low pressure output water flow at a generally uniform flow rate, notwithstanding variations in the input pressure, and resistance to clogging by impurities in the water.
It is well known that the use of a narrow passageway provides efficient pressure and flow rate reduction but involves the risk of clogging by particulate matter in the water. In this and other contexts a serpentine passageway has been found to provide enhanced pressure and flow rate reduction with a relatively wide passageway.
U.S. Pat. No. 4,466,462 describes a circuitous path flow restrictor including a fluid director member having a core and a plurality of fins extending from the core and defining alternately axially offset notches. The fluid director member is encircled by a containment member such that a serpentine fluid flow path is defined therebetween to provide a fluid flow resistance level equivalent to a simple orifice of much smaller diameter. The fluid director member can be made by a precision casting process for economy of manufacture.